1. Technical Field
The present disclosure relates generally to flow control devices and, more particularly, to a control valve which includes a discrete, multi-stage, multi-path valve trim, located in concentric cylinders, along the outlet axis of the valve, with potential to characterize flow resistance at different opening points.
2. Description of the Related Art
There is currently known in the prior art a type of control valve commonly referred to as a pintle valve wherein the short extension of a needle-valve tip is used to facilitate the control of fluid through the valve. An exemplary pintle-type fluid flow control device or control valve is described with particularity in Applicant's U.S. Pat. No. 5,803,119 entitled FLUID FLOW CONTROL DEVICE issued Sep. 8, 1998, the disclosure of which is incorporated herein by reference.
In a first embodiment of the control valve described in the '119 Patent, a cylindrical plug is moveable axially within a complimentary cylinder. The plug includes a fluid flow path extending axially therein. As the plug is moved axially relative to the cylinder, the area of path entry available for fluid flow and the length of the fluid flow path is varied. As a result, as the plug moves further out of the cylinder, a corresponding increase in fluid flow is obtained in the control valve. In a second embodiment, the plug is devoid of the aforementioned flow path, and is reciprocally movable within the bore of a tapered, annular sleeve. The sleeve is fitted into an external, solid cylinder. The outer surface of the sleeve is provided with a series of axially extending passageways, each of which fluidly communicates with the bore of the sleeve via a plurality of axially spaced and radially directed openings extending through the thickness of the sleeve. As the plug is lifted, successive openings along each passageway are exposed so that flow increases through the sleeve.
The flow control device or control valve constructed in accordance with the present invention represents an improvement over the control valve described in the '119 Patent, and in particular the second embodiment thereof, by virtue of its inclusion of more intricate and complex flow passages which each have a single entry and exit path. The increased intricacy/complexity of the flow passages within the control valve of the present invention provides for a better flow range/rangeability therethrough. These, as well as other features and advantages of the present invention, will be described in more detail below.